Adjustable tube clamping connectors have been widely used and there are many types of inner tube gripping devices in the prior art. The present invention is designed to hold the inner tube more firmly without causing any deformation or damage to the inner tube.
As shown in FIG. 1, the conventional adjustable tube clamping connector comprises an outer tube, an inner tube and a clamp. The outer tube has a longitudinal open slot in one side. The clamp is welded to the outer tube and has two lugs on the open slot. The lugs have cavities and are slightly open. When the lugs are brought together by a screw bolt and nut, the outer tube with slot will be clamped to grip and hold the inner tube firmly. To give added strength and pressure for the outer tube to grip the inner tube, two clamping pieces are fitted in the cavities of the lugs.
Also as shown in FIG. 2, the clamping piece is in inverted U shape (as shown in FIG. 2-2) and fitted in the cavity of the lug with its two ends keeping contact with the external surface of the outer tube (as shown in FIG. 2-3). When the lugs are brought together by the screw bolt and nut, the clamping pieces will make the sloted outer tube to grip and hold the inner tube firmly so that it can bear greater vertical load. But for lack of the effect of reinforcing, the lugs and the outer tube will be deformed and damaged when they are tightened by the screw bolt. As a result, it will be difficult to adjust the connection next time.
The application of another clamping piece is shown in FIGS. 3-1 and 3-3. The clamping piece in the shape of a block (as shown in FIG. 3-2) is fitted in the lug with its back perfectly contacting the bottom of the lug and its end well contacting the external surface of the outer tube. So it can give added strength and pressure to the clamp. But the clamping effect depends on the thickness of the clamping piece or the contact area of the clamping piece with the outer tube. The larger the contact area the greater the clamping force. Since such clamping pieces are made by punching press, their thickness is limited. Otherwise, it would be difficult to process and too much waste would be resulted from punching. It does not meet the economic principle of mass production. So the major disadvantage of the conventional device is the limitation thickness and the reduction of steadiness and safety in clamping.
In view of the above mentioned disadvantages, the inventor worked hard to make improvements and developed this invention. So the main object of this invention is to provide an improved adjustable tube clamping connector which has eliminated the disadvantages of the conventional connectors by employing a pair of clamping pieces with extensions which give added strength and pressure to ensure the steadiness and safety in clamping.
Another object of this invention is to provide an improved adjustable tube clamping connector of which the clamping piece can be made by punching in mass production so as to reduce the cost.